JP4263629B2 - Audio video signal synthesizer - Google Patents

Description

  The present invention provides an audio / video signal including a synthesis unit that synthesizes the plurality of audio / video signals by selecting one of a plurality of audio / video signals including the same content and outputs the synthesized audio / video signal. More particularly, the present invention relates to an audio / video signal synthesizer that synthesizes and outputs a plurality of MPEG-2 transport stream signals.

  Conventionally, in road races such as marathons for outdoor programs, in order to relay road race patterns without interruption, mobile relay vehicles equipped with cameras for shooting runners, etc., and in the vicinity of road race courses. A so-called diversity technique is used in which an audio / video signal including the same content is transmitted to and from a base station deployed in the network via a plurality of wireless lines.

  In this way, the audio / video signal including the same content transmitted using the diversity technique is synthesized into one audio / video signal by the audio / video signal synthesis apparatus.

With the recent spread of digital audio and video signals and communication technology, a plurality of compressed and encoded audio video signals, for example, MPEG-2 (Moving Picture Experts Group) transport stream signals (hereinafter referred to as MPEG-2 TS). And a plurality of MPEG-2 TSs are synthesized by selecting any MPEG-2 TS from among a plurality of MPEG-2 TSs (for example, Patent Documents). 1).
JP 2003-78913 A

  By the way, for the relay of road races such as the marathon as described above, the quality of the broadcast video is required to be improved with the spread of digital HDTV broadcasting. In order to relay the amount of information that increases as the quality of outdoor program videos increases, it is necessary to efficiently use a wireless line used for relaying outdoor programs. Therefore, a multiplexing device that multiplexes a plurality of MPEG-2 TSs is used for relaying outdoor programs.

  In this way, in an environment where the multiplexing apparatus is used for relaying an outdoor program, an MPEG-2 TS including a plurality of identical contents (programs) transmitted using diversity technology is further converted into one MPEG-2 TS. When synthesizing, the following situation can occur.

  That is, since the propagation path may be significantly different, the propagation delay difference between the combined MPEG-2 TSs becomes large. In particular, in the MPEG-2 TS transmitted through the multiplexing (separating) device and the MPEG-2 TS transmitted without using the multiplexing (separating) device, the delay caused by the length of the propagation path is small or small. The propagation delay difference is further increased depending on the presence / absence of a delay associated with the multiplexing / demultiplexing process in the multiplexing (separating) device.

  Also, the content of information indicating the state differs between an MPEG-2 TS transmitted via a multiplexing (separating) device and an MPEG-2 TS transmitted without passing through the multiplexing (separating) device.

  For example, PAT (Program Association Table) in which information for managing content (program) included in MPEG-2 TS is described, and information for managing data such as audio and video constituting the content are described. The contents of so-called program specific information (hereinafter referred to as PSI (Program Specific Information)) such as a PMT (Program Map Table) may be changed or added in some cases. In addition, in the MPEG-2 TS multiplexing or demultiplexing process, the transmission order of various packets (such as audio / video packets) constituting the MPEG-2 TS may be changed.

  In other words, the conventional diversity combining device normally creates a plurality of MPEG-2 TSs (audio / video signals) having different states depending on differences in propagation paths and the presence / absence of multiplexing / demultiplexing processing by a multiplexing (separating) device. There was a problem that it was not possible to synthesize to MPEG-2 TS.

  Therefore, the present invention has been made in view of the above points, and it is possible to normally synthesize a plurality of audio / video signals having different states depending on differences in propagation paths and the presence / absence of multiplexing / demultiplexing processing. An object of the present invention is to provide a video signal synthesis device.

  In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is that a plurality of audio / video signals are synthesized by selecting one of a plurality of audio / video signals (for example, MPEG-2 TS) including the same content. An audio / video signal synthesizing apparatus (diversity synthesizing unit 250) including a synthesizing unit that outputs a synthesized audio / video signal, and a packet constituting the audio / video signal based on program identification information (PSI) that identifies the content A synthesis target packet identification unit (packet identification unit 255a, 255b) that identifies a synthesis target packet (for example, an audio / video packet, etc.) to be synthesized from (for example, transport packets constituting MPEG-2 TS). ) And a cyclic counter (Continuity Counter) value indicating the transmission order of the compositing target packet. A first delay adjustment unit (video delay adjustment unit 261, audio delay adjustment unit 262) that adjusts the order in which the data is sent to the synthesis unit, and program reference time information that is time information included in the audio-video signal A system reference time information generator (STC counters 258a and 258b) that generates system reference time information (System Time Clock) that is time information used in the audio / video signal synthesizer based on (Program Clock Reference); A system reference time adjustment unit (STC averaging unit 266) that calculates an intermediate value of the plurality of system reference time information generated by the system reference time information generation unit, and the intermediate value calculated by the system reference time adjustment unit Program reference time addition for adding program reference time information to the synthesized audio / video signal based on And summarized in that and a (PCR adding unit 267).

  According to this feature, since the compositing target packet identification unit identifies the compositing target packet with reference to the MPEG-2 TS program identification information (PSI), specifically, the contents of the PAT and PMT, Even when a packet identifier (PID) indicating the contents of a packet is rewritten by a separation device or the like, the audio / video signal synthesis device can reliably identify the synthesis target packet.

  Further, according to such a feature, the first delay adjustment unit adjusts the order of sending the synthesis target packets to the synthesis unit based on the value of the cyclic counter (Continuity Counter) included in the MPEG-2 TS. Even when the transmission order of the compositing target packet is changed by a multiplexing (separating) device or the like, it can be adjusted to the correct order at the time of combining.

  Furthermore, according to this feature, the program reference time adding unit adds the program reference time information to the synthesized “output MPEG-2 TS” based on the intermediate value of the system standard time information. 2 TS ”jitter component, that is, output timing of“ output MPEG-2 TS ”can be prevented from greatly fluctuating.

By the way, 4 bits are allocated as the above-mentioned MPEG-2 TS cyclic counter, and the value of the cyclic counter is incremented (increased) every time a transport packet having the same PID is received. When it reaches 15 ”(2 ⁴ −1), it returns to“ 0 ”next, so the range of transport packets that can recognize the transmission order is limited to within 7 packets before and after.

  Therefore, when the difference in propagation delay of the MPEG-2 TS to be synthesized is large, specifically, when the propagation delay of the synthesis target packet is equal to or longer than the time corresponding to 15 packets, the audio / video signal synthesis device There is a possibility that MPEG-2 TS cannot be normally synthesized.

  Therefore, a second feature of the present invention is the second delay adjustment unit that approximates or matches the values of the plurality of system reference time information generated by the system reference time generation unit in the first feature of the present invention. The gist is to further include (variable delay adjustment units 252a and 252b).

  According to this feature, since the second delay adjustment unit approximates or matches the values of the plurality of system reference time information, it is possible to reduce the propagation delay difference between the combined MPEG-2 TSs.

  By approximating or matching the values of a plurality of system reference time information, in general, it is possible to converge the propagation delay difference between the synthesized MPEG-2 TSs within a time corresponding to 15 packets. The audio / video signal synthesizer can synthesize MPEG-2 TS normally even when the propagation delay difference between MPEG-2 TS is large, in combination with the operation by the first delay adjustment unit described above.

  By the way, in the multiplexing (separation) device, the program reference time information (PCR) included in the output MPEG-2 TS is replaced, but output from the multiplexing (separation) device or the like in accordance with the replacement processing. In some cases, the transmission order of the PCR packets to be changed is different from that of other packets (such as audio / video packets) compared to before the replacement process. Further, the temporal distance (time difference) between the audio / video packet and the PCR included in the PCR packet may change with the replacement process.

  Accordingly, a third feature of the present invention is that, in the first or second feature of the present invention, the first delay adjustment unit includes unit start display information (Payload Unit Start Indicator) included in each of the audio video signals. ) To detect a propagation delay difference between the plurality of audio / video signals, and adjust a combining timing, which is a timing to send the combining target packet to the combining unit, according to the detected propagation delay difference. Is the gist.

  According to this feature, the first delay adjustment unit calculates the time distance (time difference) between the audio / video packet and the PCR included in the PCR packet based on the unit start display information (Payload Unit Start Indicator). In order to recognize the audio / video signal even if the PCR packet transmission order is relatively delayed with respect to the audio / video packet or the position of the audio / video packet relative to the PCR is changed. The synthesizer can normally synthesize MPEG-2 TS.

  In the third feature of the present invention, the first delay adjustment unit recognizes the temporal distance (time difference) between the audio / video packet and the PCR included in the PCR packet more reliably. The transport of other MPEG-2 TSs in which the PID value included in the packet, the scramble control (Transport Scrambling Control) value indicating the scramble mode of the transport packet, or the adaptation field control (Adaptation Field Control) value is synthesized. It may also be determined that it matches the port packet.

  According to a fourth feature of the present invention, in the first to third features of the present invention, whether or not an error is included in the contents of the compositing target packet using an error display area provided in the compositing target packet. An error display adding unit (receiving unit 251a) for adding an error display for displaying the error, and a selection unit (video packet selecting unit 263, for selecting only a synthesis target packet to which no error display is added according to the error display. The present invention further includes an audio packet selection unit 264).

  According to such a feature, the selection unit can recognize the presence / absence of an error for each synthesis target packet, and therefore, even when the transmission order of the synthesis target packet is changed, the synthesis target packet including the error is selected. Can be recognized correctly.

  A fifth feature of the present invention is that, in the fourth feature of the present invention, when the error indication is added to the packet to be synthesized, or when synchronization information included in the packet to be synthesized cannot be recognized, The gist of the present invention is to further include an invalidating unit (video packet selecting unit 263, audio packet selecting unit 264) that invalidates a synthesis target packet positioned in a predetermined range before and after the target packet without being synthesized.

  In other words, if the number of error bits included in the packet to be combined is excessive, errors may not be detected normally, or the error correction adding unit may be delayed due to an increase in the time for correcting the error. In some cases, it is not possible to accurately exclude a synthesis target packet including an error from a synthesis target.

  According to the fifth aspect of the present invention, when the error indication is added to the compositing target packet (transport packet) or when the synchronization information included in the compositing target packet cannot be recognized, the invalidating unit By invalidating the synthesis target packet located in a predetermined range before and after the target packet, it is possible to prevent the synthesis target packet that may contain an error from being synthesized.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the invalidation unit transmits the audio / video signal input to the audio / video signal synthesizer (for example, an OFDM transceiver). The gist is that the predetermined range is set based on the time interleave length used in.

  That is, the state in which an error in the compositing target packet cannot be normally detected is related to the time interleave length used in the transmission apparatus, for example, the time length of one symbol that is a unit of information transmitted in the wireless transmission apparatus. There are many cases. According to the sixth aspect of the present invention, a compositing target packet that may contain an error can be efficiently eliminated.

  According to the present invention, there is provided an audio / video signal synthesizing apparatus capable of normally synthesizing a plurality of audio / video signals having different states depending on differences in propagation paths and presence / absence of multiplexing / demultiplexing processing. be able to.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration example of an outdoor program relay system according to the present embodiment.

  Specifically, FIG. 1 shows a configuration example of a relay system when relaying a road race such as a marathon. As shown in the figure, a center base station BS1 is provided in the vicinity of the stadium SD that is the start / goal point of the road race.

  In the vicinity of the road race course CU, mobile relay vehicles C1 and C2 equipped with cameras for shooting runners and the like, and base stations BS2 and BS3 for relaying audio / video signals via a wireless line are arranged. Has been.

  Since such road race relay is generally live broadcasting, a radio line connecting the mobile relay vehicles C1 and C2 and the temporarily installed base stations (BS1 to BS3) is very important. Therefore, the coverage of each base station is configured to overlap with the coverage of other base stations as much as possible so that MPEG-2 TS (transport stream signal) transmitted from the mobile relay vehicles C1 and C2 can be reliably relayed. The

  As shown in the figure, the center base station BS1 has a coverage CV1. Further, the base station BS2 has coverage CV2, and the base station BS3 has coverages CV3a and CV3b. For example, the coverage CV1 and the coverage CV2 have areas that overlap each other, and in the figure, the mobile relay vehicle C1 is located in the area. Similarly, the coverage CV2 and the coverage CV3a have regions that overlap each other, and the mobile relay vehicle C2 is located in the region in the figure.

  Also, in the figure, the mobile relay vehicle C1 can be connected to the center base station BS1 via the radio line RL11 and to the base station BS2 via the radio line RL12. Furthermore, the mobile relay vehicle C2 can be connected to the base station BS3 via the radio line RL21 and to the base station BS2 via the radio line RL22.

  That is, the mobile relay vehicles C1 and C2 are connected to a plurality of base stations via a radio channel, and can transmit the same MPEG-2 TS to the plurality of base stations.

  Further, as shown in the figure, the center base station BS1 and the base station BS2 are connected via the radio line RL1, and the center base station BS1 and the base station BS3 are connected via the radio line RL2.

  Further, the center base station BS1 performs processing for switching the audio and video information included in the MPEG-2 TS according to the development of the road race for the MPEG-2 TS transmitted from the mobile relay vehicles C1 and C2, A process of inserting an impose is executed. Furthermore, the MPEG-2 TS for which the processing has been executed is relayed to the broadcasting station ST via a wireless or wired line.

  In the broadcasting station ST, the MPEG-2 TS relayed from the center base station BS1 is converted into a signal in accordance with the broadcasting system if necessary. The signal is transmitted from the transmission tower TW to the viewer as a radio signal.

(Outline block configuration of relay system)
Next, a schematic block configuration of the above-described relay system will be described with reference to FIG. As shown in the figure, the mobile relay vehicle C1 includes an MPEG2 encoder 11 that encodes a video signal or the like captured by a camera (not shown) into MPEG-2 TS, and an MPEG-2 TS, which is connected to a radio line RL11. And an OFDM transmitter 21 that transmits to the base station BS2 via the radio line RL12. Similarly, the mobile relay vehicle C2 includes an MPEG2 encoder 12 and an OFDM transmitter 22 that transmits MPEG-2 TS to the base station BS2 via a radio line RL22.

  The OFDM transmitters 21 and 22 are transmitters using an orthogonal frequency division multiplex system, and in this embodiment, an 800 MHz band is used as a frequency band to be used.

  The base station BS2 includes OFDM receivers 31 and 32, an MPEG2 TS multiplexer 100, and an FM transmitter 41.

  The OFDM receiver 31 sends the MPEG-2 TS transmitted from the mobile relay vehicle C1 via the radio line RL12 to the MPEG2 TS multiplexer 100. Similarly, the OFDM receiver 32 sends the MPEG-2 TS transmitted from the mobile relay vehicle C2 via the radio line RL22 to the MPEG2 TS multiplexer 100.

  The MPEG2 TS multiplexing apparatus 100 receives a plurality of MPEG-2 TSs, multiplexes the plurality of MPEG-2 TSs, and outputs “multiplexed MPEG-2 TS”.

  The FM transmitter 41 is a digital radio transmitter using frequency modulation, and faces the FM receiver 51 provided in the center base station BS1. The FM transmitter 41 can transmit “multiplexed MPEG-2 TS” multiplexed by the MPEG2 TS multiplexer 100 to the center base station BS1 via the radio line RL1.

  Although not shown in the figure, the base station BS3 also has the same block configuration as the base station BS2.

  The center base station BS1 includes an FM receiver 51, an OFDM receiver 33, an MPEG2 TS separation / diversity combining device 200, and MPEG2 decoders 61 and 62.

  The FM receiver 51 sends “multiplexed MPEG-2 TS” transmitted from the FM transmitter 41 via the radio line RL1 to the MPEG2 TS separation / diversity combining apparatus 200.

  The OFDM receiver 33 sends the MPEG-2 TS transmitted from the mobile relay vehicle C1 via the radio line RL11 to the MPEG2 TS separation / diversity combining apparatus 200.

  The MPEG2 TS separation / diversity synthesis apparatus 200 includes an MPEG2 TS separation unit 210 and a diversity synthesis unit 250.

  The MPEG2 TS separator 210 separates “multiplexed MPEG-2 TS” multiplexed by the MPEG2 TS multiplexer 100 into MPEG-2 TS. Specifically, the MPEG2 TS separation unit 210 separates the MPEG-2 TS transmitted from the mobile relay vehicle C2 from the “multiplexed MPEG-2 TS” and sends it to the MPEG2 decoder 61. Also, the MPEG2 TS separation unit 210 sends “multiplexed MPEG-2 TS” to the diversity combining unit 250.

  The diversity combining unit 250 transmits the MPEG-2 TS transmitted from the mobile relay vehicle C1 included in the “multiplexed MPEG-2 TS” received via the FM receiver 51 and the mobile relay via the OFDM receiver 33. The MPEG-2 TS transmitted from the vehicle C1 is synthesized and one MPEG-2 TS is output to the MPEG2 decoder 62.

  The MPEG2 decoders 61 and 62 decode the MPEG-2 TS output from the MPEG2 TS separation / diversity synthesis apparatus 200 into RGB signals.

(Logic block configuration of audio video signal synthesizer)
Next, with reference to FIG. 3, the logical block configuration of the diversity synthesizer 250 constituting the audio / video signal synthesizer according to the present embodiment will be described.

  As shown in the figure, the diversity combining unit 250 includes a receiving circuit 250 a that receives the MPEG-2 TS output from the OFDM receiver 33 and a “multiplexed MPEG-2 TS” output from the MPEG2 TS demultiplexing unit 210. Receiving circuit 250b.

  The diversity combining unit 250 includes a video delay adjusting unit 261, an audio delay adjusting unit 262, a video packet selecting unit 263, an audio packet selecting unit 264, a multiplexing unit 265, an STC averaging unit 266, and a PCR. And an addition unit 267.

  Since the receiving circuit 250a and the receiving circuit 250b have the same block configuration, the block configuration of the receiving circuit 250a will be described below.

  The reception circuit 250a includes a reception unit 251a, a variable delay adjustment unit 252a, a PLL unit 253a, a packet identification unit 255a, a video buffer 256a, an audio buffer 257a, and an STC counter 258a. The packet identification unit 255a is connected to the program number selection unit 254.

  The program number selection unit 254 allows a user of the MPEG2 TS separation / diversity synthesis apparatus 200 to select a content (program number) included in the MPEG-2 TS received by the reception unit 251a. Graphical User Interface).

  Further, the program number selection unit 254, based on the program number selected by the user, PAT (Program Association Table) and PMT (Program Map Table) included in the MPEG-2 TS, that is, PSI (Program Specific Information), With reference to the program specifying information), the packet identifying unit 255a is instructed to specify a transport packet (combining target packet) to be combined. Specifically, the program number selection unit 254 instructs the packet identification unit 255a on the PID (Program Identifier) of the transport packet to be synthesized. The receiving unit 251a can correct a bit error (error) error included in the MPEG-2 TS.

  Further, the receiving unit 251a adds an error display for indicating whether or not an error is included in the content of the transport packet by using an error display area provided in the transport packet. In the present embodiment, an error display adding unit is configured.

  Here, FIG. 4 shows the structure of the MPEG-2 TS received by the receiving unit 251a. FIG. 4A shows a transport packet configured in units of 188 bytes. FIG. 4B shows the structure of the transport packet. As shown in FIG. 4B, the transport packet is provided with an adaptation field. FIG. 4C shows the configuration of the adaptation field. As shown in FIG. 4C, an optional field is provided in the adaptation field. FIG. 4D shows the configuration of the optional field.

  The receiving unit 251a adds an error display using the “error display” bit shown in FIG. That is, since the receiving unit 251a adds an error indication using an error indication bit for each transport packet, the transmission order of the transport packet is, for example, in the MPEG-2 TS multiplexing process by the MPEG2 TS multiplexer 100. Even if it is changed accordingly, the video packet selection unit 263, the audio packet selection unit 264, and the like located in the subsequent stage can correctly recognize the transport packet including the error.

  The variable delay adjustment unit 252a (252b) approximates or matches the values of the STC (System Time Clock, system reference time information) generated by the STC counters 258a and 258b, respectively. A delay adjustment unit is configured.

  Specifically, the variable delay adjustment unit 252a, together with the variable delay adjustment unit 252b, matches the STC values generated by the STC counters 258a and 258b. Here, in order to make the STC values coincide with each other, the STC value generated by the STC counter 258b may be matched with the STC value generated by the STC counter 258a, or vice versa.

  Furthermore, the variable delay adjustment units 252a and 252b may set an intermediate value between the values of each STC. Further, the variable delay adjustment units 252a and 252b do not have to completely match the values of the STCs.

  The PLL unit 253a is composed of a digital / analog converter, a low-pass filter, and a voltage controlled oscillator, and a PCR (Program Clock Reference) value included in the MPEG-2 TS received by the receiving unit 251a, The oscillation frequency of the voltage controlled oscillator is adjusted by comparing the value of the STC generated by the STC counter 258a.

  The packet identifying unit 255a identifies a compositing target packet that is a compositing target from among transport packets constituting the MPEG-2 TS based on an instruction from the program number selecting unit 254. The compositing target packet identification unit is configured.

  Specifically, the packet identification unit 255a identifies the transport packet to be synthesized based on the PID instructed by the program number selection unit 254. Also, the packet identification unit 255a includes video packets (video) and the like (including other PCR packets) among the transport packets to be synthesized in the video buffer 256a, audio packets (audio) and the like (in addition to the PCR packets). Are stored in the audio buffer 257a.

  The video buffer 256a and the audio buffer 257a can store transport packets for each PID, and have a capacity of 16 packets in this embodiment.

  The STC counter 258a generates an STC that is time information used in the audio / video signal synthesizer based on a PCR value that is time information included in the MPEG-2 TS received by the receiving unit 251a. Yes, in this embodiment, a system reference time information generation unit is configured.

  Specifically, the STC counter 258a measures the STC used in the receiving circuit 250a, that is, the time, based on the PCR value included in the received MPEG-2 TS. Also, the STC value counted by the STC counter 258a is notified to the STC averaging unit 266.

  Next, the function of a block for synthesizing MPEG-2 TS received by the receiving circuit 250a and the receiving circuit 250b will be described.

  The video delay adjustment unit 261 sends a video packet or the like included in the transport packet to the video packet selection unit 263 based on the value of a cyclic counter (Continuity Counter) indicating the transmission order of the transport packets to be combined. In this embodiment, the first delay adjustment unit is configured.

  Specifically, the video delay adjustment unit 261 determines the transport delay based on the value of the cyclic counter (see FIG. 4B) represented by 4 bits included in the transport packet to be combined. The order of sending video packets included in the packet to the video packet selection unit 263 is adjusted.

  In other words, the video delay adjusting unit 261 sends the video packet included in the transport packet to be combined included in each MPEG-2 TS received by the receiving circuit 250a and the receiving circuit 250b to the video packet selecting unit 263. The order to be performed is determined based on the value of the cyclic counter. For example, the video packet included in the transport packet whose cyclic counter value is “5” (0101) is transmitted to the video packet selection unit 263 at the same timing.

  Also, the video delay adjustment unit 261 performs a propagation delay difference between a plurality of MPEG-2 TSs based on unit start display information (Payload Unit Start Indicator, see FIG. 4B) included in each MPEG-2 TS. , And the combining timing, which is the timing for sending the video packet included in the transport packet to be combined to the video packet selecting unit 263, can be adjusted according to the detected propagation delay difference.

  The audio delay adjustment unit 262 executes the same processing as the video delay adjustment unit 261 while synchronizing with the video delay adjustment unit 261 for audio packets included in the transport packet to be combined.

  A method for adjusting the delay of the transport packet by the video delay adjusting unit 261 and the audio delay adjusting unit 262 will be described later.

  The video packet selector 263 synthesizes a plurality of MPEG-2 TSs and outputs one synthesized MPEG-2 TS (synthesized audio / video signal). In this embodiment, the video packet selector 263 constitutes a synthesizer.

  Specifically, the video packet selection unit 263 selects one of the same compositing target packets constituting each MPEG-2 TS sent from the video delay adjustment unit 261 and sends it to the multiplexing unit 265. Send it out.

  Further, the video packet selection unit 263 selects only the compositing target packet to which no error display is added according to the error display added by the reception unit 251a, and constitutes a selection unit in this embodiment. Specifically, the video packet selection unit 263 selects only packets that do not have an error indication and sends them to the multiplexing unit 265.

  Further, the video packet selection unit 263, when an error indication is added to the transport packet to be synthesized, or the synchronization information included in the transport packet to be synthesized (synchronization byte, see FIG. 4B) Cannot be recognized without synthesizing the transport packet to be synthesized located in a predetermined range before and after the transport packet to be synthesized, and in this embodiment, the invalidation unit is Constitute.

  Specifically, the video packet selection unit 263 can invalidate a transport packet including an error indication and 7 to 4095 packets before and after the transport packet.

  In addition, the video packet selection unit 263 is configured such that the predetermined range described above can be set based on the time interleave length used in the transmission apparatus that transmits the MPEG-2 TS input to the reception unit 251a.

  Specifically, in the video packet selection unit 263, a transport packet corresponding to the same time as the time interleave length (symbol length) used in the OFDM receivers 31 to 33 or twice the time interleave length. Can be set to be invalidated.

  The audio packet selection unit 264 executes processing similar to that of the video packet selection unit 263 while synchronizing with the video packet selection unit 263 for audio packets included in the transport packet to be synthesized.

  The multiplexing unit 265 multiplexes the synthesized video packets and audio packets output from the video packet selection unit 263 and the audio packet selection unit 264 and converts them into one MPEG-2 TS.

  The STC averaging unit 266 calculates an intermediate value of a plurality of STCs (system reference time information) generated by the STC counters 258a and 258b, and constitutes a system reference time adjustment unit in this embodiment.

  Specifically, the STC averaging unit 266 calculates the average value of the STC values generated by the STC counters 258a and 258b, respectively. That is, the STC averaging unit 266 calculates the average value by dividing the total value of the STC value generated by the STC counter 258a and the STC value generated by the STC counter 258b by “2”. To do.

  Note that the STC averaging unit 266 may determine an intermediate value between the STC value generated by the STC counter 258a and the STC value generated by the STC counter 258b, instead of a simple average value.

  Based on the average value (intermediate value) calculated by the STC averaging unit 266, the PCR adding unit 267 performs PCR (MPEG-2 TS output from the multiplexing unit 265, that is, the synthesized MPEG-2 TS with PCR ( Program reference time information) is added, and in this embodiment, a program reference time addition unit is configured.

  Specifically, as shown in FIG. 4D, the PCR adding unit 267 is calculated by the STC averaging unit 266 using a PCR field (for example, 42 bits) provided in the optional field. The average value of the STC is added as PCR.

(Operation of audio / video signal synthesizer)
Next, with reference to FIG. 5 and FIG. 6, the operation of the diversity synthesizer 250 constituting the audio / video signal synthesizer according to this embodiment will be described.

  First, with reference to FIG. 5, an operation in which diversity combining section 250 adjusts a propagation delay difference between received MPEG-2 TSs will be described. Here, (a1) in the figure shows the MPEG-2 TS input to the receiving circuit 250a, that is, the MPEG-2 TS output by the OFDM receiver 33 (hereinafter referred to as MPEG-2 TSa) as described above. Is shown. On the other hand, FIG. 2B1 shows the MPEG-2 TS input to the receiving circuit 250b, that is, as described above, the MPEG-2 TS output by the MPEG2 TS separation unit 210 (hereinafter referred to as MPEG-2 TSb). Is shown.

  As shown in (a1) and (b1), MPEG-2 TSb is input to diversity combining section 250 via MPEG2 TS multiplexing apparatus 100 and MPEG2 TS demultiplexing section 210, so that it is more efficient than MPEG-2 TSa. Delayed (arrow in the figure) is input to the receiving circuit 250b.

  Accordingly, diversity combining section 250 (video delay adjusting section 261 and audio delay adjusting section 262) performs MPEG based on the value of a cyclic counter field (not shown) included in MPEG-2 TSa and MPEG-2 TSb. -2 The order of combining packets included in TSa and MPEG-2 TSb, and the combining timing are adjusted.

  Specifically, the video delay adjustment unit 261 (audio delay adjustment unit 262) sends the video packet selection unit 263 (audio packet selection unit 264) MPEG-2 based on the value of the cyclic counter (Continuity Counter) field. The order or timing of sending each packet of TSa and MPEG-2 TSb (each square part in the figure) is adjusted.

  Also, diversity combining section 250 (variable delay adjustment sections 252a and 252b) matches the STC values generated based on MPEG-2 TSa and MPEG-2 TSb in receiving circuit 250a and receiving circuit 250b, respectively. The propagation delay difference between MPEG-2 TSa and MPEG-2 TSb is adjusted.

That is, 4 bits are allocated as the cyclic counter of MPEG-2 TSa and MPEG-2 TSb, and the value of the cyclic counter is incremented (increased) every time a transport packet having the same PID is received, When the value becomes “15” (2 ⁴ −1), it returns to “0” next, so the range of transport packets that can recognize the transmission order is limited to within 7 packets before and after (arrows in the figure). The Therefore, when the propagation delay difference between MPEG-2 TSa and MPEG-2 TSb is equal to or longer than the time corresponding to 15 packets, diversity combining section 250 normally combines MPEG-2 TSa and MPEG-2 TSb. You may not be able to. Therefore, as described above, the variable delay adjustment units 252a and 252b match the values of the STC generated based on the MPEG-2 TSa and the MPEG-2 TSb, respectively, so that the MPEG-2 TSa and the MPEG-2 TSb are matched. And further, that is, reduce the propagation delay difference.

  5 (a2) and 5 (b2) show that the order of synthesis and the synthesis timing of MPEG-2 TSa and MPEG-2 TSb are based on the PCR packet base, that is, the time by matching the values of the cyclic counter and the STC. The state adjusted based on the information is shown (the timings of Pa_pcr1 and Pb_pcr1 and Pa_pcr2 and Pb_pcr2 in the figure match).

  In addition, the PCR value is changed in the MPEG2 TS multiplexer 100 and the like, but the transmission order of the PCR packets output from the MPEG2 TS multiplexer 100 and the like is compared with that before the replacement process in accordance with the replacement process. Thus, there may be a relative delay from audio / video packets (AV packets) or the like.

  That is, as shown in FIGS. 5 (b1) and (b2), the MPEG-2 TSb PCR packet (Pb_pcr1) input via the MPEG2 TS multiplexer 100 and the MPEG2 TS demultiplexing unit 210 is MPEG-2 TSa. In comparison, it is relatively behind the AV packet (Pb_av) and the unit start display packet (Pb_st).

  Specifically, as shown in (b1) and (b2) of the figure, in MPEG-2 TSb, Pb_st is located immediately after Pb_pcr1, and the MPEG- shown in (a1) and (a2) of FIG. 2 Compared with TSa, Pb_pcr1 is relatively delayed from the AV packet (Pb_av) and the unit start display packet (Pb_st).

  In such a case, the video delay adjusting unit 261 (audio delay adjusting unit 262) adjusts the order and combining timing of combining each packet of MPEG-2 TSa and MPEG-2 TSb based on the PCR packet base, that is, time information. However, there is a problem because packets having the same contents cannot be sent to the video packet selection unit 263 (audio packet selection unit 264).

  Therefore, as shown in FIGS. 5 (a3) and (b3), the video delay adjustment unit 261 (audio delay adjustment unit 262) performs unit start display (Payload Unit Start Indicator) included in MPEG-2 TSa and MPEG-2 TSb. ) Based on the packets (Pa_st, Pb_st), the synthesis order and synthesis timing of each packet included in the MPEG-2 TSa and the MPEG-2 TSb can be adjusted.

  That is, when the unit start indication packet expressed by 1 bit is “1”, the payload of the transport packet, that is, the PES (Packetized Elementary Stream) packet configured by the AV packet is started from the first byte. It shows that. Therefore, the video delay adjustment unit 261 (audio delay adjustment unit 262) recognizes the time distance (time difference) between the unit start display packet and the specific AV packet (Pa_av, Pb_av) specified by the unit start display packet. By doing so, the order and timing for synthesizing the packets of MPEG-2 TSa and MPEG-2 TSb are adjusted.

  In FIGS. 5 (a3) and (b3), MPEG-2 TSa and MPEG-2 TSb are based on unit start indication packets (Pa_st, Pb_st) and AV packets (Pa_av, Pb_av) specified by Pa_st, Pb_st. The order of combining the packets included in the packet and the combining timing are adjusted.

  Note that the diversity combining unit 250 (the video delay adjusting unit 261 and the audio delay adjusting unit 262) recognizes the temporal distance (time difference) between the AV packet and the PCR included in the PCR packet more reliably. -Transcoding of other MPEG-2 TS to which the PID value included in the packet, the scramble control (Transport Scrambling Control) value indicating the scramble mode of the transport packet, or the adaptation field control (Adaptation Field Control) value is synthesized It may also be determined that it matches the port packet.

  In addition, in an MPEG-2 TS multiplexing (separation) device (for example, MPEG2 TS multiplexing device 100), the PCR value included in the output MPEG-2 TS is replaced. The temporal distance (time difference) between the video packet and the PCR included in the PCR packet may change.

  FIG. 6 is an explanatory diagram for explaining the change in the positional relationship between the audio / video packet and the PCR packet (within the PCR) accompanying the PCR value replacement process.

  FIG. 6A shows the STC counter value generated from the PCR value included in the MPEG-2 TS input to the MPEG-2 TS multiplexing (separating) device (for example, the MPEG2 TS multiplexing device 100).

  FIG. 6D shows an STC counter value (for example, MPEG2) generated from a PCR value included in the MPEG-2 TS output from an MPEG-2 TS multiplexing (separating) apparatus (for example, MPEG2 TS multiplexing apparatus 100). 4 shows an STC counter value generated in the MPEG2 decoder 61 that receives and decodes the MPEG-2 TS output from the TS multiplexer 100.

  Since the STC counter values shown in FIGS. 4A and 4D are generated based on the same PCR value, they have the same time information (timing).

  FIG. 2B shows each packet constituting the transport packet of MPEG-2 TS inputted to the MPEG-2 TS multiplexing (separating) device. In FIG. 5B, the numbers (1, 10, 15 etc.) shown in the lower part of each packet indicate the time stamp value included in the packet.

  Note that the time indicated by the time stamp (“PCR 1”, “PCR 11” in the figure) included in the PCR packet coincides with the time by the STC counter value shown in FIG. (See the dashed line with arrows in the figure).

  The MPEG-2 TS video packet “V10” shown in FIG. 5B is the MPEG-2 TS multiplexing (separating) device when the STC counter value shown in FIG. Has been entered. In other words, the reception time (“3”) of the video packet and the reproduction (or decoding) time (“10”) are “processing waiting time” for “7” counts (the solid line with an arrow in the figure represents reference).

  Further, FIG. 6C shows each packet constituting an MPEG-2 TS transport packet output from the MPEG-2 TS multiplexing (separating) device. In FIG. 4C, the numbers (3, 10, 15, etc.) shown in the lower part of each packet indicate the value of the time stamp included in the packet.

  The timing at which the MPEG-2 TS transport packet shown in FIG. 3C is output from the MPEG-2 TS multiplexing (separating) device is multiplexed (separated) by the MPEG-2 TS multiplexing (separating) device. As a result of the processing, the packet is delayed by two packets from the MPEG-2 TS transport packet input to the MPEG-2 TS multiplexing (separating) device shown in FIG.

  Therefore, with the PCR value replacement process by the MPEG-2 TS multiplexing (separation) device, the content of the time stamp of “PCR 1” in FIG. 5B is changed (“1” → “3”). As shown in (c) of the same figure, it is changed to “PCR 3”.

  Here, in a general MPEG-2 TS multiplexing (separation) device or the like, a PCR value replacement process is executed without considering the processing delay in the MPEG-2 TS multiplexing (separation) device itself.

  For this reason, the MPEG-2 TS video packet “V10” shown in FIG. 8C is MPEG-2 TS multiplexed (when the value of the STC counter shown in FIG. Output from the separation device.

  Therefore, in the MPEG2 decoder (for example, the MPEG2 decoder 61) that receives and decodes the MPEG-2 TS, the reception time (“5”) of the video packet and the reproduction (or decoding) time (“10”). Means “processing waiting time” for “5” counts (see solid line with arrow in the figure).

  That is, at the time of input to the MPEG-2 TS multiplexing (separating) device, the “processing waiting time” was “7” counts, but due to the processing delay of the MPEG-2 TS multiplexing (separating) device, “ The “processing waiting time” (temporal distance) decreases to “5” counts.

  That is, when the MPEG-2 TS passes through such an MPEG-2 TS multiplexing (separation) device, even if the STC counter values are matched based on the PCR values included in the MPEG-2 TSa and the MPEG-2 TSb, respectively. Therefore, the position of the audio / video packet is shifted by “2” counts.

  As described above, diversity combining section 250 according to the present embodiment can adjust the order and combining timing for combining each packet of MPEG-2 TSa and MPEG-2 TSb based on the unit start display packet. Therefore, even in the cases shown in FIGS. 6A to 6D, the order of combining the packets and the combining timing can be adjusted.

  Next, with reference to FIG. 7, the operation of the diversity combining unit 250 adjusting the PCR value added to the combined MPEG-2 TS will be described.

  Here, FIG. 5A shows MPEG-2 TSa input to the receiving circuit 250a, that is, MPEG-2 TS output by the OFDM receiver 33. On the other hand, FIG. 5B shows MPEG-2 TSb input to the receiving circuit 250b, that is, MPEG-2 TS output by the MPEG2 TS separation unit 210.

  Since the MPEG-2 TSa shown in FIG. 6A is directly input to the diversity combining unit 250 via the OFDM receiver 33, the jitter component (variation delay) is reduced (each square in the figure). The distance between them is almost uniform).

  On the other hand, since the MPEG-2 TSb shown in FIG. 5B is input to the diversity combining unit 250 via the MPEG2 TS multiplexing apparatus 100 and the MPEG2 TS demultiplexing unit 210, the jitter component increases (in the figure). The distance between each square is not uniform). Also, MPEG-2 TSb has a longer propagation path than MPEG-2 TSa, and passes through MPEG2 TS multiplexer 100, so that fixed delay FD increases.

  FIG. 3C shows the temporal positional relationship of each packet included in MPEG-2 TSa and MPEG-2 TSb. In FIG. 3C, ta indicates time, and tr indicates a temporal distance (time difference) from the previous packet.

  Pa represents an ideal input time of each packet included in the MPEG-2 TSa (that is, there is no jitter component), and Pb represents an ideal input of each packet included in the MPEG-2 TSb. Indicates the time.

  The diversity combining unit 250 averages the PCR value included in the MPEG-2 TSa and the STC value generated by the PCR value included in the MPEG-2 TSb, and the average value of the MPEG-2 TS after combining is averaged. The PCR value is stored in the PCR packet.

  That is, time information that is located on Pav located between Pa and Pb shown in FIG. 5C is added as a PCR value of the synthesized MPEG-2 TS. Note that the added PCR value may be a value not located on Pav as long as it is a value located between Pa and Pb.

  As mentioned above, although one embodiment of the present invention has been described using MPEG-2 as an example, the scope of application of the present invention should not be construed as being limited to MPEG-2. That is, the present invention can be applied to an audio / video signal synthesizer that operates based on program reference time information that is time information included in an audio / video signal and system reference time information that is time information used in a multiplexing device. it can.

(Action / Effect)
According to the diversity combining unit 250 according to this embodiment described above, the packet identifying unit 255a refers to the MPEG-2 TS program identification information (PSI), specifically, the contents of the PAT and PMT, and combines them. Even when the PID indicating the packet content is rewritten by the MPEG2 TS multiplexing apparatus 100 or the like to identify the target transport packet, the diversity combining unit 250 reliably identifies the transport packet to be combined. be able to.

  According to the diversity combining unit 250 according to the present embodiment, the video delay adjusting unit 261 and the audio delay adjusting unit 262 transmit the transport packet to be combined based on the value of the cyclic counter included in the MPEG-2 TS. Therefore, even if the transmission order of the transport packets to be combined is changed by the MPEG2 TS multiplexer 100 or the like, it can be adjusted to the correct order at the time of combining.

  According to the diversity combining unit 250 according to the present embodiment, the PCR adding unit 267 adds a PCR value to the combined “output MPEG-2 TS” based on the intermediate value of the STC. The jitter component of “TS”, that is, the output timing of “output MPEG-2 TS” can be suppressed from greatly fluctuating.

  According to the diversity combining unit 250 according to the present embodiment, the variable delay adjustment units 252a and 252b approximate or match the STC values used for MPEG-2 TSa and MPEG-2 TSb. The propagation delay difference between them can be reduced.

  By approximating or matching the values of the plurality of STCs, in general, the propagation delay difference between the combined MPEG-2 TSs can be converged within a time corresponding to 15 packets. In combination with the operations performed by the video delay adjustment unit 261 and the audio delay adjustment unit 262, the MPEG-2 TS can be normally combined even when the propagation delay difference between the MPEG-2 TSs is large.

  According to diversity combining section 250 according to the present embodiment, video delay adjustment section 261 and audio delay adjustment section 262 are included in audio / video packets and PCR packets based on unit start display information (Payload Unit Start Indicator). In order to recognize the time distance (time difference) with the PCR to be transmitted, the PCR packet transmission order is delayed relative to the audio / video packet due to the PCR replacement process, etc. Even when the position with respect to the PCR packet changes, the MPEG-2 TS can be normally synthesized.

It is a figure which shows the structural example of the relay system of the outdoor program which concerns on embodiment of this invention. It is a figure which shows schematic block structure of the relay system of the outdoor program which concerns on embodiment of this invention. It is a figure which shows the logic block structure of the audio video signal synthesizer which concerns on embodiment of this invention. It is a figure which shows the structure of the audio video signal synthesize | combined in the audio video signal synthesizer which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the operation | movement of adjustment of the propagation delay difference by the audio video signal synthesizer according to the embodiment of the present invention. It is explanatory drawing for demonstrating the operation | movement of adjustment of the propagation delay difference by the audio video signal synthesizer according to the embodiment of the present invention. It is explanatory drawing for demonstrating the replacement | exchange operation | movement of the program reference time information by the audio video signal synthesizer concerning the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... MPEG2 TS multiplexing apparatus, 11, 12 ... MPEG2 encoder, 21, 22 ... OFDM transmitter, 31, 32, 33 ... OFDM receiver, 41 ... FM transmitter, 51 ... FM receiver, 61, 62 ... MPEG2 decoder 200 ... MPEG2 TS separation / diversity synthesis device 210 ... MPEG2 TS separation unit 250 ... diversity diversity unit 250a, 250b ... reception circuit 251a, 251b ... reception unit, 252a, 252b ... variable delay adjustment unit, 253a, 253b ... PLL section, 254 ... program number selection section, 255a, 255b ... packet identification section, 256a, 256b ... video buffer, 257a, 257b ... audio buffer, 258a, 258b ... STC counter, 261 ... video delay adjustment section, 262 ... Audio delay adjustment unit, 263 ... Bidet Packet selection unit, 264 ... audio packet selection unit, 265 ... multiplexing unit, 266 ... STC averaging unit, 267 ... PCR addition unit, BS1 ... center base station, BS2, BS3 ... base station, C1, C2 ... mobile relay vehicle CU ... Course, CV1, CV2, CV3a, CV3b ... Coverage, RL1, RL2, RL11, RL12, RL21, RL22 ... Radio link, SD ... Stadium, ST ... Broadcasting station, TW ... Transmission tower

Claims (6)

An audio / video signal synthesizer including a synthesis unit that synthesizes the plurality of audio / video signals by selecting one of a plurality of audio / video signals including the same content and outputs the synthesized audio / video signal. And
A compositing target packet identifying unit that identifies a compositing target packet that is a compositing target from among the packets constituting the audio / video signal based on the program specifying information that specifies the content;
A first delay adjustment unit that adjusts an order of sending the synthesis target packet to the synthesis unit based on a value of a cyclic counter indicating a transmission order of the synthesis target packet;
A system reference time information generating unit that generates system reference time information that is time information used in the audio and video signal synthesizer, based on program reference time information that is time information included in the audio and video signal;
A system reference time adjusting unit that calculates an intermediate value of the plurality of system reference time information generated by the system reference time information generating unit;
An audio / video signal synthesizing apparatus comprising: a program reference time adding unit that adds program reference time information to the synthesized audio / video signal based on the intermediate value calculated by the system reference time adjusting unit.   The audio / video signal synthesizer according to claim 1, further comprising a second delay adjustment unit that approximates or matches a plurality of values of the system reference time information generated by the system reference time generation unit.   The first delay adjustment unit detects a propagation delay difference between the plurality of audio / video signals based on unit start display information included in each of the audio / video signals, and according to the detected propagation delay difference The audio / video signal synthesizing apparatus according to claim 1, wherein a synthesis timing, which is a timing at which the synthesis target packet is transmitted to the synthesis unit, is adjusted. Using an error display area provided in the packet to be combined, an error display adding unit for adding an error display for indicating whether or not the content of the packet to be combined includes an error;
4. The audio / video signal synthesizer according to claim 1, further comprising: a selection unit that selects only a synthesis target packet to which the error indication is not added according to the error indication. 5. .   When the error indication is added to the synthesis target packet, or when the synchronization information included in the synthesis target packet cannot be recognized, the synthesis target packet located in a predetermined range before and after the synthesis target packet is not synthesized. The audio / video signal synthesizing apparatus according to claim 4, further comprising a disabling unit that disables the disabling unit. 6. The predetermined range based on a time interleave length used in a transmission device that transmits the audio / video signal input to the audio / video signal synthesis device is set in the invalidation unit. The audio-video signal synthesis device according to 1.

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